A* Pathfinding Project  3.8
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RandomPath Class Reference

Finds a path in a random direction from the start node. More...

Detailed Description

Finds a path in a random direction from the start node.

Terminates and returns when G >= length (passed to the constructor) + RandomPath.spread or when there are no more nodes left to search.

//Call a RandomPath call like this, assumes that a Seeker is attached to the GameObject
//The path will be returned when the path is over a specified length (or more accurately has "costed" more than a specific value)
int theGScoreToStopAt = 50;
//Create a path object
RandomPath path = RandomPath.Construct (transform.position, theGScoreToStopAt);
//Get the Seeker component which must be attached to this GameObject
Seeker seeker = GetComponent<Seeker>();
//Start the path and return the result to MyCompleteFunction (which is a function you have to define, the name can of course be changed)
seeker.StartPath (path,MyCompleteFunction);
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Public Member Functions

 RandomPath ()
 
 RandomPath (Vector3 start, int length, OnPathDelegate callback=null)
 
override void CalculateStep (long targetTick)
 Calculates the path until completed or until the time has passed targetTick.
 
override void Initialize ()
 Initializes the path.
 
override void Prepare ()
 Prepares the path.
 
override void Reset ()
 Reset all values to their default values.
 
override void ReturnPath ()
 Calls callback to return the calculated path.
 
- Public Member Functions inherited from ABPath
override void Cleanup ()
 Always called after the path has been calculated.
 
override string DebugString (PathLog logMode)
 Returns a debug string for this path.
 
override uint GetConnectionSpecialCost (GraphNode a, GraphNode b, uint currentCost)
 May be called by graph nodes to get a special cost for some connections.
 
Vector3 GetMovementVector (Vector3 point)
 Returns in which direction to move from a point on the path.
 
void ResetCosts (Path p)
 Resets End Node Costs.
 
 ABPath ()
 Default constructor.
 
- Public Member Functions inherited from Path
void AdvanceState (PathState s)
 Threadsafe increment of the state.
 
uint CalculateHScore (GraphNode node)
 Estimated cost from the specified node to the target.
 
bool CanTraverse (GraphNode node)
 Returns if the node can be traversed.
 
void Claim (System.Object o)
 Claim this path (pooling).
 
void Error ()
 Aborts the path because of an error.
 
void ForceLogError (string msg)
 Logs an error and calls Error().
 
Int3 GetHTarget ()
 
PathState GetState ()
 Returns the state of the path in the pathfinding pipeline.
 
uint GetTagPenalty (int tag)
 Returns penalty for the given tag.
 
float GetTotalLength ()
 Total Length of the path.
 
uint GetTraversalCost (GraphNode node)
 
bool IsDone ()
 Returns if this path is done calculating.
 
void Log (string msg)
 Appends a message to the errorLog.
 
void LogError (string msg)
 Appends msg to errorLog and logs msg to the console.
 
virtual void OnEnterPool ()
 Called when the path enters the pool.
 
void Release (System.Object o, bool silent=false)
 Releases a path claim (pooling).
 
void ReleaseSilent (System.Object o)
 Releases the path silently (pooling).
 
IEnumerator WaitForPath ()
 Waits until this path has been calculated and returned.
 

Static Public Member Functions

static RandomPath Construct (Vector3 start, int length, OnPathDelegate callback=null)
 
- Static Public Member Functions inherited from ABPath
static ABPath Construct (Vector3 start, Vector3 end, OnPathDelegate callback=null)
 Construct a path with a start and end point.
 

Public Attributes

Vector3 aim
 An aim can be used to guide the pathfinder to not take totally random paths.
 
float aimStrength
 If an aim is set, the higher this value is, the more it will try to reach aim.
 
int searchLength
 G score to stop searching at.
 
int spread
 All G scores between searchLength and searchLength+spread are valid end points, a random one of them is chosen as the final point.
 
bool uniform
 
- Public Attributes inherited from ABPath
bool calculatePartial
 Calculate partial path if the target node cannot be reached.
 
GraphNode endHint
 Hints can be set to enable faster Get Nearest Node queries.
 
GraphNode endNode
 End node of the path.
 
Vector3 endPoint
 End point of the path.
 
Vector3 originalEndPoint
 End Point exactly as in the path request.
 
Vector3 originalStartPoint
 Start Point exactly as in the path request.
 
bool recalcStartEndCosts = true
 Defines if start and end nodes will have their connection costs recalculated for this path.
 
GraphNode startHint
 Hints can be set to enable faster Get Nearest Node queries.
 
Int3 startIntPoint
 Start point in integer coordinates.
 
GraphNode startNode
 Start node of the path.
 
Vector3 startPoint
 Start point of the path.
 
- Public Attributes inherited from Path
OnPathDelegate callback
 Callback to call when the path is complete.
 
float duration
 The duration of this path in ms.
 
int enabledTags = -1
 Which graph tags are traversable.
 
Heuristic heuristic
 Determines which heuristic to use.
 
float heuristicScale = 1F
 Scale of the heuristic values.
 
OnPathDelegate immediateCallback
 Immediate callback to call when the path is complete.
 
NNConstraint nnConstraint = PathNNConstraint.Default
 Constraint for how to search for nodes.
 
List< GraphNodepath
 Holds the path as a Node array.
 
int searchedNodes
 Number of nodes this path has searched.
 
int searchIterations
 The number of frames/iterations this path has executed.
 
List< Vector3 > vectorPath
 Holds the (perhaps post processed) path as a Vector3 list.
 

Protected Member Functions

RandomPath Setup (Vector3 start, int length, OnPathDelegate callback)
 
- Protected Member Functions inherited from ABPath
virtual void CompletePathIfStartIsValidTarget ()
 Checks if the start node is the target and complete the path if that is the case.
 
void UpdateStartEnd (Vector3 start, Vector3 end)
 Sets the start and end points.
 
void Setup (Vector3 start, Vector3 end, OnPathDelegate callbackDelegate)
 
- Protected Member Functions inherited from Path
void DebugStringPrefix (PathLog logMode, System.Text.StringBuilder text)
 Writes text shared for all overrides of DebugString to the string builder.
 
void DebugStringSuffix (PathLog logMode, System.Text.StringBuilder text)
 Writes text shared for all overrides of DebugString to the string builder.
 
bool HasExceededTime (int searchedNodes, long targetTime)
 
virtual void Trace (PathNode from)
 Traces the calculated path from the end node to the start.
 

Properties

override bool FloodingPath [get]
 
override bool hasEndPoint [get]
 
- Properties inherited from ABPath
virtual bool hasEndPoint [get]
 Determines if a search for an end node should be done.
 
- Properties inherited from Path
System.DateTime callTime [get, set]
 When the call was made to start the pathfinding for this path.
 
PathCompleteState CompleteState [get, set]
 Current state of the path.
 
bool error [get]
 If the path failed, this is true.
 
string errorLog [get]
 Log messages with info about eventual errors.
 
virtual bool FloodingPath [get]
 True for paths that want to search all nodes and not jump over nodes as optimizations.
 
PathHandler pathHandler [get, set]
 Data for the thread calculating this path.
 
ushort pathID [get, set]
 ID of this path.
 
bool recycled [get, set]
 True if the path is currently recycled (i.e in the path pool).
 
int[] tagPenalties [get, set]
 Penalties for each tag.
 

Private Attributes

PathNode chosenNodeR
 Currently chosen end node.
 
int maxGScore
 The G score of maxGScoreNodeR.
 
PathNode maxGScoreNodeR
 The node with the highest G score which is still lower than searchLength.
 
int nodesEvaluatedRep
 
readonly System.Random rnd = new System.Random()
 Random class.
 

Additional Inherited Members

- Protected Attributes inherited from ABPath
int[] endNodeCosts
 Saved original costs for the end node.
 
PathNode partialBestTarget
 Current best target for the partial path.
 
- Package Functions inherited from Path
void PrepareBase (PathHandler pathHandler)
 Prepares low level path variables for calculation.
 
- Package Attributes inherited from Path
Path next
 Internal linked list implementation.
 
bool pooled
 True if the path is currently pooled.
 

Constructor & Destructor Documentation

RandomPath ( Vector3  start,
int  length,
OnPathDelegate  callback = null 
)

Member Function Documentation

override void CalculateStep ( long  targetTick)
virtual

Calculates the path until completed or until the time has passed targetTick.

Usually a check is only done every 500 nodes if the time has passed targetTick. Time/Ticks are got from System.DateTime.UtcNow.Ticks.

Basic outline of what the function does for the standard path (Pathfinding.ABPath).

while the end has not been found and no error has ocurred
check if we have reached the end
if so, exit and return the path
open the current node, i.e loop through its neighbours, mark them as visited and put them on a heap
check if there are still nodes left to process (or have we searched the whole graph)
if there are none, flag error and exit
pop the next node of the heap and set it as current
check if the function has exceeded the time limit
if so, return and wait for the function to get called again

Reimplemented from ABPath.

static RandomPath Construct ( Vector3  start,
int  length,
OnPathDelegate  callback = null 
)
static
override void Initialize ( )
virtual

Initializes the path.

Sets up the open list and adds the first node to it

Reimplemented from ABPath.

override void Prepare ( )
virtual

Prepares the path.

Searches for start and end nodes and does some simple checking if a path is at all possible

Reimplemented from ABPath.

override void Reset ( )
virtual

Reset all values to their default values.

All inheriting path types must implement this function, resetting ALL their variables to enable recycling of paths. Call this base function in inheriting types with base.Reset ();

Reimplemented from ABPath.

override void ReturnPath ( )
virtual

Calls callback to return the calculated path.

See Also
callback

Reimplemented from Path.

RandomPath Setup ( Vector3  start,
int  length,
OnPathDelegate  callback 
)
protected

Member Data Documentation

Vector3 aim

An aim can be used to guide the pathfinder to not take totally random paths.

For example you might want your AI to continue in generally the same direction as before, then you can specify aim to be transform.postion + transform.forward*10 which will make it more often take paths nearer that point

See Also
aimStrength
float aimStrength

If an aim is set, the higher this value is, the more it will try to reach aim.

PathNode chosenNodeR
private

Currently chosen end node.

int maxGScore
private

The G score of maxGScoreNodeR.

PathNode maxGScoreNodeR
private

The node with the highest G score which is still lower than searchLength.

Used as a backup if a node with a G score higher than searchLength could not be found

int nodesEvaluatedRep
private
readonly System.Random rnd = new System.Random()
private

Random class.

int searchLength

G score to stop searching at.

The G score is rougly the distance to get from the start node to a node multiplied by 100 (per default, see Pathfinding.Int3.Precision), plus any eventual penalties

int spread

All G scores between searchLength and searchLength+spread are valid end points, a random one of them is chosen as the final point.

On grid graphs a low spread usually works (but keep it higher than nodeSize*100 since that it the default cost of moving between two nodes), on NavMesh graphs I would recommend a higher spread so it can evaluate more nodes

bool uniform

Property Documentation

override bool FloodingPath
get
override bool hasEndPoint
getprotected

The documentation for this class was generated from the following file: